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- // Copyright (c) 2016-2017, The Tor Project, Inc. */
- // See LICENSE for licensing information */
- use libc::{c_char, c_void};
- use std::{ptr, slice, mem};
- #[cfg(not(test))]
- extern "C" {
- fn tor_malloc_(size: usize) -> *mut c_void;
- }
- // Defined only for tests, used for testing purposes, so that we don't need
- // to link to tor C files. Uses the system allocator
- #[cfg(test)]
- unsafe extern "C" fn tor_malloc_(size: usize) -> *mut c_void {
- use libc::malloc;
- malloc(size)
- }
- /// Allocate memory using tor_malloc_ and copy an existing string into the
- /// allocated buffer, returning a pointer that can later be called in C.
- ///
- /// # Inputs
- ///
- /// * `src`, a reference to a String.
- ///
- /// # Returns
- ///
- /// A `*mut c_char` that should be freed by tor_free in C
- ///
- pub fn allocate_and_copy_string(src: &String) -> *mut c_char {
- let bytes: &[u8] = src.as_bytes();
- let size = mem::size_of_val::<[u8]>(bytes);
- let size_one_byte = mem::size_of::<u8>();
- // handle integer overflow when adding one to the calculated length
- let size_with_null_byte = match size.checked_add(size_one_byte) {
- Some(n) => n,
- None => return ptr::null_mut(),
- };
- let dest = unsafe { tor_malloc_(size_with_null_byte) as *mut u8 };
- if dest.is_null() {
- return ptr::null_mut();
- }
- unsafe { ptr::copy_nonoverlapping(bytes.as_ptr(), dest, size) };
- // set the last byte as null, using the ability to index into a slice
- // rather than doing pointer arithmatic
- let slice = unsafe { slice::from_raw_parts_mut(dest, size_with_null_byte) };
- slice[size] = 0; // add a null terminator
- dest as *mut c_char
- }
- #[cfg(test)]
- mod test {
- #[test]
- fn test_allocate_and_copy_string_with_empty() {
- use std::ffi::CStr;
- use libc::{free, c_void};
- use tor_allocate::allocate_and_copy_string;
- let empty = String::new();
- let allocated_empty = allocate_and_copy_string(&empty);
- let allocated_empty_rust =
- unsafe { CStr::from_ptr(allocated_empty).to_str().unwrap() };
- assert_eq!("", allocated_empty_rust);
- unsafe { free(allocated_empty as *mut c_void) };
- }
- #[test]
- fn test_allocate_and_copy_string_with_not_empty_string() {
- use std::ffi::CStr;
- use libc::{free, c_void};
- use tor_allocate::allocate_and_copy_string;
- let empty = String::from("foo bar biz");
- let allocated_empty = allocate_and_copy_string(&empty);
- let allocated_empty_rust =
- unsafe { CStr::from_ptr(allocated_empty).to_str().unwrap() };
- assert_eq!("foo bar biz", allocated_empty_rust);
- unsafe { free(allocated_empty as *mut c_void) };
- }
- }
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